When the two domains are started on a UNIX/Linux system, a port conflict
error is thrown and the second instance fails to start. However, when the
two domains are started on Windows 2000/XP, no error is thrown, both server
instances start, but only the first instance is accessible at the specified
port. When that first server instance is subsequently shut down, the second
instance then becomes accessible. Moreover, when both instance are running,
the Windows netstat command shows the duplicate listeners
as active, but only the first listener can respond to requests.

Solution

Be sure to use unique port numbers for all server instances on Windows
systems.